The Government yesterday unveiled detailed preparations on how the UK would cope in the event of a deadly flu pandemic.

Health Secretary John Reid announced that 14.6 million doses of the anti-viral drug Tamiflu, costing #200m, would be stockpiled in case of a flu outbreak that could potentially kill more than 50,000 Britons.

Chief medical officer Sir Liam Donaldson outlined other measures to reduce the spread of the virus, including the possibility of closing schools and cancelling football matches and concerts.

But experts warned that relying on a vaccine against flu was of no use in the short-term, as the exact strain of virus would not be known until the pandemic struck. The plan follows warnings from the World Health Organisation (WHO) last week that a new strain of bird flu could develop, meaning the virus could spread from human to human.

Avian flu, which is spread from birds to humans, has already killed more than 40 people in Asia since 2003.

The last flu pandemic - Hong Kong flu in 1968 - killed more than one million people, including 30,000 Britons.

The biggest flu pandemic of the last century was in 1918, when Spanish flu killed 50 million people - including 250,000 Britons.

If human-to-human transmission of a bird flu strain develops, experts believe a pandemic could spread rapidly across the world.

Despite a successful winter flu vaccination programme, between 12,000 and 18,000 people die a year from "seasonal" flu in Britain, mainly among high-risk groups such as the elderly.

But pandemic flu is different, with the potential to affect a much larger proportion of the population, with experts suggesting around one in four of the UK population could be affected.

The ordinary winter flu vaccine would not be effective against a pandemic strain. Anti-viral drugs are not a cure but can reduce the severity of flu symptoms and slow down the spread of the virus.

Sir Liam said that, while there were calls to do more to create a vaccine quicker, the UK was leading the world in its scientific preparations.

A vaccine could not be made until the virus involved in any pandemic was identified and it would not be possible to predict what strain will emerge.

He said after a pandemic emerged, it could take four to six months to produce an effective vaccine against the strain involved.

Dr Reid said if a pandemic did emerge, its impact could be severe.

"We are working closely with other Governments and the WHO to ensure the international community is as well prepared as it can be to spot and address the early signs of a pandemic as quickly as possible.

"However, it makes sense to ensure that we in the UK are as prepared as we can be and have drugs for use against an influenza pandemic here."

Flu facts

What is pandemic flu?

It is a highly infectious potentially fatal viral illness which spreads easily from person to person either through the air or via hand/face contact. It is a novel virus to which the population has very little or no immunity.

When will it happen?

Experts cannot predict this but say it could come in two or more waves several months apart and with each wave lasting two or three months. Pandemic flu occurs every few decades, spreads rapidly and hits most countries. It could strike at any time of the year, resulting in thousands of deaths.

What are the symptoms?

It is likely to cause the same symptoms as ordinary flu but have a more serious impact.

What impact will a pandemic have?

Anything between two million and 50 million deaths and the possibility of more than 50,000 additional deaths in the UK. It would also cause economic disruption, put intense pressure on health and other services and interfere with daily life. There is no way to predict the full damage.

What is it caused by?

Flu pandemics are triggered by a new flu virus which is markedly different from recently circulating strains and to which few, if any, people have any immunity. This allows it to spread widely, easily and to cause more serious illness.

Who is at risk?

Everyone. Certain groups may be at greater risk than others but until the virus starts circulating no one knows for sure who they will be.

Is there a vaccine?

There is no vaccine ready as the outbreak would have been caused by a new virus which has to be identified. It is near impossible to predict what the new strain will be. Ordinary flu vaccines and the flu jab will be ineffective. Anti-viral drugs will have to be used but their effectiveness would only become known once the pandemic has taken hold.

What should people do?

Maintaining good basic hygiene, such as washing your hands, may help prevent spreading the virus. Other advice includes covering your nose and mouth when coughing and sneezing and trying to avoid crowds.

But once you have caught the flu you should stay at home and rest, take medicines to relieve the symptoms and drink plenty of fluids.